HAEMATOIDIN. 301 



ZALESKI considers this pigment as a hydrogenized haemin. A regenera- 

 tion of haematin from haematoporphyrin has been performed by LAID- 

 LAW. If haematoporphyrin is dissolved in dilute ammonia and warmed 

 with STOKES' solution and hydrazine hydrate, iron is taken up again 

 and haemochromogen is produced, which is changed into hsematin by 

 shaking with air. According to HAM and BALEAN/ it is possible to pro- 

 duce haemoglobin from haemochromogen and globin, and it is indeed 

 possible that other proteins can replace globin in this formation. 



Haematoidin, thus called by VIRCHOW, is a pigment which crystallizes 

 in orange-colored rhombic plates, and which occurs in old blood extrav- 

 asations, and whose origin from the blood-coloring matters seems to 

 be established (LANGHANS, CORDUA, QUINCKE, and others 2 ). A solu- 

 tion of haematoidin shows no absorption-bands, but only a strong absorp- 

 tion from the violet to the green (EWALD 3 ) . According to most observers, 

 haematoidin is identical with the bile-pigment bilirubin. It is not 

 identical with the crystallizable lutein from the corpora lutea of the ovaries 

 of the cow (PICCOLO and LiEBEN, 4 KUHNE and EWALD). 



In the detection of the above-described blood-coloring matters the 

 spectroscope is the only entirely trustworthy means of investigation. 

 If it is only necessary to test for blood in general and not to determine 

 definitely whether the coloring-matter is haemoglobin, methaemoglobin 

 or haematin, then the preparation of haemin crystals is an absolutely 

 positive test. In regard to the detection of blood in urine, see Chapter 

 XIV, and for the detection of blood in intestinal contents, in pathological 

 fluids and in chemi co-legal cases we must refer the reader to more extended 

 text-books. 



The methods proposed for the quantitative estimation of the blood- 

 coloring matters are partly chemical and partly physical. 



Among the chemical methods to be mentioned is the incineration of the 

 .blood and the determination of the amount of iron contained in the ash from 

 which the amount of hemoglobin may be calculated. We must refer to works 

 on chemical methods of investigation in regard to these methods. 



The physical methods consist either of colorimetric or of spectroscopic 

 investigations. 



The principle of HOPPE-SEYLER'S colorimetric method is that a measured 

 quantity of blood is diluted with an exactly measured quantity of water 

 until the diluted blood solution has the same color as a pure oxyhaemo- 

 globin solution of a known strength. The amount of coloring-matter 

 present in the undiluted blood may be easily calculated from the degree 

 of dilution. In the colorimetric testing we use a glass vessel with parallel 



1 Zaleski, Zeitschr. f. physiol. Chem., 43; Laidlaw, Journ. of Physiol., 31; Ham 

 and Balean, ibid., 32. 



2 A comprehensive review of the literature pertaining to haematoidin may be found 

 in Stadelmann, Der Icterus, etc., Stuttgart, 1891, pp. 3 and 45. 



3 Zeitschr. f. Biologic, 22, 475. 



4 Cit. from Gorup-Besanez, Lehrbuch d. physiol. Chem., 4. Aufl., 1878. 



